Harden D&D scene description extraction

internal/modules/dnd/codec/scenedescriptions/assets/schemas/dnd_scene_descriptions.v1.json

@@ -7,6 +7,7 @@
   "properties": {
     "scenes": {
       "type": "array",
+      "minItems": 1,
       "items": {
         "type": "object",
         "additionalProperties": false,

internal/modules/dnd/codec/scenedescriptions/codec.go

@@ -97,6 +97,9 @@ func validate(value dnd.SceneDescriptionList) error {
 	if value.Scenes == nil {
 		return fmt.Errorf("scenes must be present")
 	}
+	if len(value.Scenes) == 0 {
+		return fmt.Errorf("scenes must not be empty")
+	}
 	for index, scene := range value.Scenes {
 		prefix := fmt.Sprintf("scenes[%d]", index)
 		if strings.TrimSpace(scene.ID) == "" {

internal/modules/dnd/codec/scenedescriptions/codec_test.go

@@ -8,6 +8,8 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/santhosh-tekuri/jsonschema/v6"
+
 	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
 	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
 	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
@@ -86,6 +88,40 @@ func TestCodecOwnsDurableSchemaAndMetadata(t *testing.T) {
 	}
 }
 
+func TestDurableSchemaRequiresAtLeastOneScene(t *testing.T) {
+	schemaDocument, err := jsonschema.UnmarshalJSON(bytes.NewReader(New().Schema().JSONSchema))
+	if err != nil {
+		t.Fatal(err)
+	}
+	compiler := jsonschema.NewCompiler()
+	if err := compiler.AddResource("schema.json", schemaDocument); err != nil {
+		t.Fatal(err)
+	}
+	compiled, err := compiler.Compile("schema.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, test := range []struct {
+		name    string
+		content []byte
+		valid   bool
+	}{
+		{name: "one scene", content: mustEncode(t, validList()), valid: true},
+		{name: "empty scenes", content: []byte(`{"scenes":[]}`)},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			instance, err := jsonschema.UnmarshalJSON(bytes.NewReader(test.content))
+			if err != nil {
+				t.Fatal(err)
+			}
+			err = compiled.Validate(instance)
+			if (err == nil) != test.valid {
+				t.Fatalf("Validate() error = %v, want valid=%t", err, test.valid)
+			}
+		})
+	}
+}
+
 func TestCodecStrictlyRejectsInvalidDurableBoundaries(t *testing.T) {
 	validJSON := `{"scenes":[{"id":"chunk-000001","source_ref":{"source_id":"session","start_unit_id":1,"end_unit_id":1},"kind":"narrative","title":"Arrival","summary":"The party arrives."}]}`
 	tests := []struct{ name, raw, want string }{
@@ -95,6 +131,7 @@ func TestCodecStrictlyRejectsInvalidDurableBoundaries(t *testing.T) {
 		{"unknown source field", strings.Replace(validJSON, `"end_unit_id":1`, `"end_unit_id":1,"unexpected":true`, 1), "unknown field"},
 		{"trailing", `{"scenes":[]} {}`, "multiple JSON values"},
 		{"missing scenes", `{}`, "scenes must be present"},
+		{"empty scenes", `{"scenes":[]}`, "scenes must not be empty"},
 		{"invalid kind", strings.Replace(validJSON, `"kind":"narrative"`, `"kind":"other"`, 1), "kind must be supported"},
 		{"blank title", strings.Replace(validJSON, `"title":"Arrival"`, `"title":" "`, 1), "title must not be empty"},
 		{"blank summary", strings.Replace(validJSON, `"summary":"The party arrives."`, `"summary":" "`, 1), "summary must not be empty"},
@@ -138,6 +175,7 @@ func TestCodecRejectsRequiredApprovedValues(t *testing.T) {
 		want  string
 	}{
 		{"nil scenes", dnd.SceneDescriptionList{}, "scenes must be present"},
+		{"empty scenes", dnd.SceneDescriptionList{Scenes: []dnd.SceneDescription{}}, "scenes must not be empty"},
 		{"empty ID", mutate(validList(), func(value *dnd.SceneDescriptionList) { value.Scenes[0].ID = " " }), "id must not be empty"},
 		{"unsupported kind", mutate(validList(), func(value *dnd.SceneDescriptionList) { value.Scenes[0].Kind = "unsupported" }), "kind must be supported"},
 		{"empty title", mutate(validList(), func(value *dnd.SceneDescriptionList) { value.Scenes[0].Title = " " }), "title must not be empty"},
@@ -155,6 +193,15 @@ func TestCodecRejectsRequiredApprovedValues(t *testing.T) {
 	}
 }
 
+func mustEncode(t *testing.T, value dnd.SceneDescriptionList) []byte {
+	t.Helper()
+	content, err := json.Marshal(value)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return content
+}
+
 func mutate(value dnd.SceneDescriptionList, change func(*dnd.SceneDescriptionList)) dnd.SceneDescriptionList {
 	change(&value)
 	return value